Reciprocating drive



Nov. 18, 1941. `w. E. Nom/ELI. 2,262,814

RECIPROCATING DRIVE Filed May 18, 1939 2 sheets-sheet 1 a .l WHQL 4l 46 ,50 45 ATTORNEY Nov. 18, 1941. w-E NQRVELL 2,262,814 Y RECIPROCATING DRIVE Fild May 18, 1 959 2 sheets-sheet 2 INVENTOR W/Y//dm f. Nof'vc BY @M TTORNEY Patented Nov. 18, 1941 UNITED STATES PATENT OFFICE RECIPROCATING DRIVE William E. Norvell, Kansas City, Mo.

Application May 18, 1939, Serial No. 274,359

7 Claims.

My invention relates to a reciprocating drive, and more particularly to a drive of thisl character for producing short rapid reciprocations of a member such as are required for various apparatus having a shaking motion, such as sorters, bolters, sifters, or other devices, requiring such motion.

It is a common practice to reciprocate a member requiring such a rapid reciprocating motion by means of an eccentric mounted on a shaft and connected with the member that is to be rapidly reciprocated. Numerous objections eX- ist in the use of an eccentric drive of this character, because of the nature of such a drive, one of the principal objections being to the fact that there is not only movement of the rod or other member, connected with the eccentric sleeve and with the member to be reciprocated, in a direction lengthwise of itself to produce the reciprocating motion, 'but there is a movement of at least one end of the rod-like member, or connecting member, between the eccentric sleeve and the member to be reciprocated, in a direc-y tion substantially perpendicular to the direction in which reciprocation is desired. This causes a whipping acton of the rod-like member connecting the eccentric sleeve with the member that is to be reciprocated. This whipping action becomes somewhat rhythmic, due to the fact that the rate of rotation is constant and causes undesirable vibrations in a direction perpendicular to the direction desired of the member that is to be reciprocated, as well as undesirable strains Jon the rod-like member that serves as a driving connection between the eccentric and the member to be reciprocated, this' being particularly objectionable in any sorting, sifting, or screening mechansm. y

The other principal objection, to reciprocating a member by means of an eccentric drive of the character above mentioned, is that the change in direction of movement takes place so suddenly that there is a tendency,l due to the inertia of the parts, to continue movement in the same direction, causing what might be referred to as backlash, in the reciprocation of the member that is driven by the eccentric. This sudden change in direction of movement occurs atboth ends of the stroke and, of course, also transversely of the connecting'member, or driving member, midway between the ends of the stroke in both directions, during the whippingaction above referredto.

'Itis the principal purpose of my invention to provide means for driving a member that must be rapidly reciprocated, in a manner vsuch that all the whipping action and all of the shock, or backlash, caused by sudden reversal of movement at the opposite ends of the reciprocation, are eliminated. This is accomplished by providing a drive in which the rotative motion of a shaft is changed into a reciprocating motion by eccentric driving means, and this reciprocating motion is utilized to produce a cushioned, substantially straight line, reciprocating motion, by utilization of a compressiblev fluid acted on by the shaft driven means to actuate the straight line reciprocating drive. This is accomplished by providing means for creating changes in pressure in a pair of chambers, so that one chamber will have a decrease below atmospheric pressure therein take place at the same time that the other chamber has an increase above atmospheric pressure taking place therein, and utilizing flexible diaphragms responsive to the changes in pressure between that in thev chambers and :that in the atmosphere to drive a driving member that is connected directly with the apparatus that is to be reciprocated. The diaphragms referred to above, are, preferably, arranged in substantial parallelism with the driving means connected substantially centrally thereto, the connections with the diaphragms being in axial alignment with each other, so that the connection between the driving member and the diaphragms aids in holding the driving member in a position to reciprocate lengthwise of itself in substantially a straight line.

It is a further purpose 4of my invention to provide means for controlling the amplitude of the reciprocation produced `by my improved means for Vproducing a reciprocating( motion, which comprises means for controlling the variations in'pressure created in the chambers above referred to, comprising by-pass means and means for controlling the passage of compressible fluid through said by-pass means to control the pressure changes in the chambers above referred to, and also comprising means for varying the rate of rotation of the shaft carrying the eccentrics, whereby the lenth o-f stroke can also be controlled.

More specically, my invention has for its purpose' the provision of an apparatus comprising a pair of diaphragms that comprise walls of chambers that are sealed rfrom the atmosphere and contain a compressible fluid,v which are connected with eccentric means so mounted on a shaft `that one diaphragm is moved `in a direction to decrease the size of the chamber with which it is associated at the same time that the other diaphragm increases the size of the chamber with which it is associated, and a pair `of chambers having diaphragms forming one `of the walls of each thereof, to which the driving effective size of which is controlled by a valve, which can also completely cut the chambers connected by the by-pass off from eachother.

It will be obvious that the rate at which exure of the mechanically actuated diaphragms takes place will affect the length o f th strokvprodiametrically opposite the peripheral portion of the eccentric 22 that is nearest the shaft I9. The eccentrics may be constructed in any desired manner, and as will be evident from Figs. 3 and 5.' Said eccentrics each have an eccentric portion 23 that is xed to the shaft to rotate therewith, and a sleeve 24, which is spaced from the eccentric portion 23, the'portion 23 being freely rotatable within the sleeve portion 24, due to the provision of ball bearings 25 between the sleeve portion and the portion 23 keyed to the shaft.

'Y The sleeve portion 24 of the eccentric 2| has farod-like member 26 secured thereto in any suitable .mannen and the sleeve portion 24 of the eccentric 22 has a similar rod-like member` r` 21 secured thereto in the same way. Said rodduced by the fluid pressure actuated dia-l phragms, due to the fact that there 'will, of course, bea certain amount of luidfrictior through the passagesfconnecting the various chambers, and that accordingly the more rapid-A ly the shaft is rotated, the shorter the stroke will be. Also, due to the provision of the by-pass, the length of the stroke of :the reciprocating motion, or amplitude thereof, 'can be. varied within Very fine limits for anyone speed at which the shaft may rotate.

, Other objects and advantages of my. invention will appear as the description of the drawings proceeds. I desire to have it understood, however, that I do not intend tovlimit myself to the particular details shown or described, except as defined in the claims.

In the drawings: Fig. 1 is a view in side elevation of my improved reciprocating driving means, showing the same attached to a member to be reciprocated, such as a bolter sieve. Y

Fig. 2 is a front elevational view, partly broken away, of my improved reciprocating driving means, on a somewhat enlarged scale.

, Fig. 3 is a section, partly broken away, taken onfthe line 3-3 of Fig. 2, on an enlarged scale, but showing the diaphragms unflexed.

Fig. 4 is a section takenon the line 4 4-0 Fig. 2, on a somewhat reduced sca-le. i i v Fig. 5 is a section taken on the line; 5'-,5`of Fig. 2, on a somewhatenlarged scale. Fig. 6l is a fragmentary section, on vran en-- larged scale, showing the by-passgand valve controlling the by-pass passage, andY l Fig. '1 is a fragmentary section taken on the line 5--5 of Fig. 7, but showing the diaphragm unflexed. v Y l o V Referring in detail to the drawings, my improved reciprocating drive is shown as being mounted on a frame having'longitudinal frame members I0, vertical frame members vand longitudinal framek members I2. A motor |3is mounted on a transverse frame member I4, or in any other suitable'manner, and'is provided with a pair of pulleys IS-and I6 for driving the drive wheel |1 at a plurality of speeds througha belt, or similar driving member, v |8, said driving pulley |1 being mounted on a shaft .-|9 to .rotate therewith, said shaft being mounted'insuitable bearings 29, provided on thel vertical frame members I I The shaft |9 has a pair of eccentrics" 2| and 22 mounted thereon, said eccentrics being mount,- ed so as to be spaced l8degreesgapa'rt` von'the' shaft I9, thatis, the peripheral portion of the eccentric 2|, that is the nearestl the shaft I9',

like members 26 and 21 are xed to the sleeve members ,24, so as to move therewith as said sleeve members 24 are moved up and down, due

toy the eccentric members 23 within the sleeves 24. Obviously the leccentric member 2 3 will 'ca use some sideward movement ofthe eccentric sleeve 24 withinwhich the same` is mounted, as'wellas vertical movement thereof. In fact the end of the member 26 or 21, as the case may be, that is secured to the sleeve 24, will have as much horizontal as vertical movement. However, this will not be true of the upper ends of therod-like members 26 and 21, as 'will be obvious as the de` soription proceeds.

My improved drive comprises a-body portion 28, which is secured to the frame members I0 by means of angle brackets 29.4` Said bodyportion is provided with a pair of chambers having the wall portions 3|)y formed integral with the body portion 28, and the flexible wall portions 3| and 32 providing chambers 33Y between the Wall portions 30 and the flexible wall portions '3| and 32, respectively. The wall portions 3| and 32 are diaphragms that are'secured tothe annular seats v34 provided therefor, by means of the clamping rings 35, which are secured in po-v sition by any suitable means, such as the headed fastening elements 36. The ends of the rodlike members 26 and 21 that are remote from the eccentric sleeves 24 are secured in uid tight* relation with the diaphragms 3| .and 32, by means of a pair of clamping washers 31, provided on opposite sides of the diaphragm members andthe nuts'38 and 39, which engage the threads proproachftheinner faces of the conical wall por- 1 be flexed downwardly at its center.

tions 30 of the chambers 33. It will be obvious that when the rod 21 is projected upwardly to its limit by the'eccentric 22, it will flex the center portion of the diaphragm 32 inwardly toward the wall 30 to provide theV minimum'capacity4 for the chamberv 33.4 Preferably, the' diaphragm 32 in that position, will substantially` engage the wall 30. At that time the diaphragm 3| will be exed downwardly at its center the same amount that the diaphragm 32 will be flexed upwardly at its center, and the chamber 33lassociated therewith will have its maximum capacity. In Fig.v

2 the eccentrics 2| and 22 are shown in such position that the diaphragm 32 will be flexed up wardly at its center, andthe diaphragm Y3| will Such upward .flexing of the diaphragmvis Iclearly shown inFig.5.` fj. f..

The body portion 28 is provided with a passage 42, thatgextends fromthe chamber .33 of. which the diaphragm 3|= forms a wall,and with a passage 43, that extendsfrom,l the chamber 33.` of which the diaphragm 32 forms'.` a wall, said: passages being separated byr a web portion 44, as will be evident from Fig, 4. The passage 42r opens at 45 into a recess 46 inzthe body portion 28, the passage- 43 opens at 41 'into a recess 48. in the body portion 28, said recesses 46and148 providing chambers within the body portion 44 connected, respectively, with' the chambers back of the diaphragms 3| and 32. The` body portion is also provided with thickened portions 49v at opposite ends thereof, to which the angle brack-v ets 29 are connected. The walls 50 of the recesses 46 and 48 are substantially conical, as will be evident from Figs. 3 and 4, and the por,- tions 45 and 41 of the passages 42 and 43 form recesses that accommodate certain of the movable parts carried lby the diaphragms 5| :and

52 cooperating with the wall 50 of each of the recesses 46 and 48-to provide aj second pair of chambers within the body portion 28.

The conical wall portions 50, providing the recesses 46 and 48, are provided with peripheral thickened portions surrounding the same forming annular seats 53 for theldiaphragms 5| and 52', saiddiaphragms being clamped to said seats by means of the clamping rings 54, and suitable fastening elements, such as the headed securing elements 55, to thus provide chambers that are sealed from the atmosphere. A driving member comprising a U-shaped, or yoke-like, member 55,. which is substantially T-shaped in cross section and which terminates in a pairof enlargements 51, is provided, to be operated by the flexing of the diaphragms 5| and 52 in opposite directions. A screw-threaded rod-like member 58 is secured to the diaphragm 5| in uid tight relation thereto, by means of the clamping washers 59' and a pair of nuts engaging the threaded rodlike member 58 to clamp said washers 59 to the diaphragm 5|. The Vscrew-threaded rod-like member 58 extends through an opening `in the enlargement 51 and is secured in xed position to the yoke-like member 56, by means of the clamping nuts 60 and suitable washers mounted between said nuts and the enlargement 51.

A screw-threaded rod-like member 6| is secured-to the other enlargement 51 on the yokelike member 56 in a similar manner to that described, and has a similar connection with the diaphragm 52, as will be obvious from Fig. 3. The screw-threaded rod-like member 6| and the rod-like member 58 are thus connected'together to move as a unit, by means of the yoke-like member 56, and due to the fact that both the rod-like member 6| and the rod-like member 58 are fixed to the centerv of the diaphragms to which the same are connected, and are co-axial, the combined action of the two diaphragms will move the rod-like member 6|' in a straight line lengthwise of itself. Due to the fact that the eccentrics 2| and 22 are mounted 180 degrees.

apart on the shaft I9, the diaphragm 32 will be flexed downwardly when the diaphragm 3| is flexed upwardly, and vice versa. When the diaphragm 3|', for example, is flexed upwardly, the diaphragm 5| will be flexed outwardly, due to the increase in pressure in the chamber formed back of the diaphragm 5| in the recess 46, and when the diaphragm 3|v is flexed downwardly,

the diaphragm 5| will be moved inwardlydueto the fact that the pressure Vin the chamber formedY back ofV the .diaphragm 5| will be: de-f creased: below atmospheric' pressure, the atmosd pheric pressure acting'. on. the` outer face of thev diaphragm 51|:4 The diaphragm 52 will operatel in a' similar' manner, and it will be obvious that when' the' diaphragm-.52 is flexed. to the right in. Fig. 3, due to increasefin pressure'in the chamber back of the same, thev diaphragm 5| will be'flexed tothe right, dueto 'decrease in pressure in the.A chamber back ofthe same, and vice versa. Ac-. cordingly the: pressure condition in the two chambers willoperate in a;V cooperative manner to "moverthe. member Blin a` reciprocating move-- ment lengthwise of itself.

A .Due;to .the fact thata certain amount of fluidA friction exists in the` 'relatively restrictedv passages42 andw4'3, there'will be a certain amount oflag in the.: change in pressure in the chambers;

back ofthe diaphragms 5| andV 52 relative tov the: y change.' in pressure inthe chambers back of the:

diaphragms 3| andv 32, due tothe positive'flexing of said' diaphragms. 3| and 32 by means of the-` eccentrics 2| and 22; Furthermore,v due tol the `fact that the space vsealed from the air within the member 28 is lledlwith air at atmosphericU pressure before the mechanism is sealed, which constitutes .an elastic or compressible lfluid medium, a certain amountof compression of therl fluidn' any ofthe chambers would take placethe eccentric 23 will move the sleeve-like member before any appreciable movement of the elastic diaphragm takes place, and also the reduction in pressure below atmospheric in the chamber in which such condition exists back of the dia. phragm 5| or 52, as the case may be, will reach a certain amount before the atmospheric pressure will appreciably flex the diaphragm asso-` ciated with such chamber. in which a pressure be v low atmospheric'exists.

Due to these facts,1the Sudden reversals in motion that take place in the reciprocating movement of the rods 2B and 21 are modified and cushioned when transmitted through-the mechanism described, to the rod 6|, thus preventing. any backlash, or shock, due t'o sudden change in direction of movement' of the parts, and producing a similar cushioned movement in the: reciprocations of the member 62, which is to'be reciprocated by means of the mechanism', saidy member 62 beingV shown inv the drawings as being a tray-like member with a flange 63 thereon, with which the rod'-like member is rigidly connected by means of the clamping nuts B4 engaging opposite faces of said flangev 63, and. screw-threadedly engaged with a screw-threaded end portion on the rod-likev member 6|'. Said. member 62is shown as being mounted for a limited reciprocating movement in a manner commonly used for members that havei a shaking movement, such as sifters, or bolters, by means of pairs of reeds, or elastic rod-like mem.- bers, 65, which are clamped by means of suitable clamping means 65 to the member 62' and to a frame member l5'. The mounting for the member 52 and the particular' configuration of the.v

motion, of relatively ksmall amplitude,l can Abev operated by my improved means for producing a cushioned reciprocating movement.

It lwill also b-e noted, that dueto the fact that 24 both laterally and vertically, as viewed in Fig. 5, a connection between a rod-like member 25, or 21, and a member to be reciprocated,

would cause a certain amount of whipping` actionA OVeI'.

bertransmitted to the member ythat was to beI shaken,sor reciprocated, thereby, causing undesirable :forces to be .exertedthereom producing a :vibratory movement a direction perpendicular-tofthe direction of thereciprocation desired. In sorting, sifting,.or. grading `apparatus having a shaking motion in substantially a plane, this vertical vibration, or whipping motion, causes the material Ythat is being acted Yupon to be whipped up Vand down, preventing 'good sorting; 'Ihis whipping action is entirely eliminated by my improved driving means, because the rod-like members 26 and 21 are connected with the flexible diaphragms 3| and 32, which will ex sufciently to take care of this'lateral movement of the' lower ends of the members 26 and 2'1, due to the, actionof the eccentrics, and the movement resulting from the movementof the dia- 'A phragms 5| and 52 transmitted tothe driving memberl will be a movement that will be entirely'free of any such whipping motion, being a true straight linereciprocating movement in the direction of length of the driving member 6|, thusremoving any undesirable vertical vibration from a screen or other member reciprocated thereby and producing a smooth back and forth motion, producing the desired shaking motion, in substantially a plane, of the stock moving there- The body portion 28` is provided with a passage 61'. and valve 68, said passage 61 being shown in Fig. 3,v andmore clearly in Fig. 6, connecting the recesses 46 and 48 in the body portion 28, and thus connecting the chambers back of the diaphragms| and 52. An enlargement 69 is pro-v vided in the'body portion`28, depending therefrom and having a screw-threaded opening 10 therein 'for receiving the screw-threadedv -end portion'1|"ofthe valve member 68, said valve member 'being merely a screw-threaded rodlikeV member having an end portion 12' extendingA substantially horizontally and screw-threaded"y into the screw-threaded opening 10, so as to'y make aHA substantially air tight connection with the' opening in the enlargement 69, and having" its inner end portion seated in a recess 13 in the body portion28 between the two Vchambers 46 and 48.

they passage 61 between the two chambers thus formed in the body portion is closed, but it be-` ing obvious that the handle 12 can be turned tol any" angular position desired, to get any desired.'

amount of opening of the"passage 61.

' It will be obvious that the greater the opening through the passage 61 is, the more the effectI of the movement of the diaphragms 3| and 32 I6() on the movement of the member 6| will be modied,"as this passage connects a chamber in which there 'would be a pressure below atmosphericp with a chamber in which there would be a pressure above atmospheric.

towardthe chamber in which the lower pressure exists, thus decreasing thev amount that the diaphragms 5| and 52 will' Vbe flexed, due to the pressures existing in the chambers back ofi,A the same. I

or recipro'catingimotion, can be adjusted,` very finely. The amplitudeof the reciprocating motion will also vary in accordance with the speed at which theshaft is rotated. A variation inamlplitude ofl lthe vibrating, or reciprocating movement, of the member 62 between A3 inch and 1A inch has been obtained by rotating the shaft at the higher speed, and a variation inv ber reciprocated by' each of said eccentrics, a'

diaphragm connected with each of said last mentioned members, a pair of chambers sealed from the atmosphere an external wall of each of which is formedb-y one of said. diaphragms, a

4 secondpair of chambers sealed from'the atmosphere each connected with one of said first mentioned chambers by a passage sealed from the atmosphere, a pair of diaphragms, each forming an external wall of oneofsaid second mentioned chambers, said chambers and passages forming ar sealed system, a compressibleuid in said Said member '13 is" provided with a transverse opening '14"that': is adapted to be aligned with the passage 61, the valve being shown in Fig. 6 as. being in a position such that "Ithas beenfound that with the'mechanism above'described,' the amplitude of the vibration, 75

chambers, a driving member connected with both saidl last mentioned diaphragms to reciprocate v lengthwise of itself, means for varying the effec-v -tiverpressure changes producedin said second chambers during a cycle of movements of said diaphragm wallsv of said rst chambers to adjust the vamplitude ofthe reciprocating movement of said driving member produced by said mechanism, and means for connecting said driving member with said member mounted for reciprocating movement.

2.y The combination with al member mounted for reciprocating movement and a rotatable.y 5f shaft, ofmeans for producing a rapid reciprocating movement of said member by rotation of said shaft, comprisingA a pair of eccentrics mounted degrees ,apart on said shaft, a member reciprocated by each of said eccentrics, aldiaphragm connected with each of said last mentioned members'a pair of chambers sealed fromfthe atmosphere a wall of each of which is formedby one of said diaphragms, a second pair of lchambers sealed from. the atmosphere each connected with one of said first mentioned chambers by'apassage, va Apair of diaphragms, each.

forming a wall of one of said second mentioned chambers, an adjustable by-pass connection-between said second mentioned chambers, a comlpressibleiiuid in said chambers, a driving vmember connected with both said last mentioned diaphragmsto reciprocate lengthwise of itself, and

means for connecting said driving member with said member mounted for eciprocating movement, Y

3. An apparatus ofthe character described,l

comprising a shaft, means forvrotating said shaftL'a pair of ,eccentrics mounted 180 degrees apartV on said shaft, a, member reciprocated by each of ysaid eccentrics, a' diaphragm connected with each of said last mentioned members, a pair of chambers sealed fromA the atmosphere an ex-I ternal wall of each of which said j diaphragms; a second sealed from the atmosphere each connected with is formed by one of: pair of chambers f one of said first mentioned chambers by a passage sealed from the atmosphere, a pair of diaphragms, each forming a wall of one of said second mentioned chambers, one face of each of said last mentioned diaphragms being exposed to atmospheric pressure, said chambers and passages forming a sealed system, a compressible iiuid in said chambers and passages, a driving member connected with both said last mentioned diaphragms to reciprocate lengthwise of itself. means for varying the eiective pressure changes produced in said second chambers during a cycle of movements of said diaphragm Walls of said first chambers to adjust the amplitude of the reciprocating movement of said driving member produced by said mechanism, and means for connecting said driving member with a member mounted for reciprocation.

4. An apparatus of the character described, comprising a shaft, means for rotating said shaft, a pair of ec-centrics mounted 180 degrees apart on said shaft, a member reciprocated by each of said eccentrics, a diaphragm connected with each of said last mentioned members, a pair of chambers sealed from the atmosphere a wall of each of which is formed by one of said diaphragms, a second pair of chambers sealed from the atmosphere each connected with one `of said rst mentioned chambers by a passage, a pair of diaphragms, each forming a wall of one of said second mentioned chambers, one face of each of said last mentioned diaphragms being exposed to atmospheric pressure, a by-pass between said second mentioned chambers, an adjustable valve controlling iow of fluid through said by-pass, a compressible fluid in said chambers, a driving member connected with both said last mentioned diaphragms to reciprocate lengthwise of itself, and means for connecting said driving member with a member mounted for reciprocation.

5. The combination with a shaft, means for rotating the same and a member to be reciprocated, of a pair of aligned, oppositely disposed chambers, a oompressible fluid therein, reciprocable means driven by said shaft to simultaneously decrease the uid pressure in one of said chambers below that of the atmosphere and ncrease that in the other of said chambers above that of the atmosphere, said reciprocable means having a constant stroke, an adjustable member for simultaneously varying the changes in pressure in both said chambers produced by the strokes of said reciprocable means responsive to rotation of said shaft, diaphragms mounted to flex responsive to the difference in pressure between the atmosphere and that of the fluid in said chambers, and a driving member connected with both of said diaphragms to reciprocate lengthwise of itself and with the member to be reciprocated.

6. The combination with a shaft, means for rotating the same and a member to be reciprocated, of a member having a pair of oppositely directed aligned recesses therein, seats around the peripheries of said recesses, fiexible diaphragms mounted on said seats to provide a pair of chambers sealed from the atmosphere having a compressible uid therein, means driven by said shaft to simultaneously decrease the uid pressure in one of said chambers below that of the atmosphere and increase that in the other of said chambers above that of the atmosphere, a yokelike driving member connected centrally with both of said diaphragms on opposite sides of said member having said recesses, said connections between said driving member and said diaphragms being in alignment with each other and means connecting said driving member with said member to be reciprocated.

7. An apparatus of the character described comprising a body portion having a pair of recesses therein at opposite ends thereof opening in the same direction, seats surrounding said recesses, iexible diaphragms mounted on said seats to provide a pair of chambers sealed from the atmosphere, a shaft, means for rotating said shaft, means connecting said diaphragms and shaft to flex said diaphragms in opposite directions during rotation of said shaft, said body portion having a pair of oppositely directed aligned recesses therein, seats surrounding said last mentioned recesses, flexible diaphragms mounted on said last mentioned seats to provide a second pairV of chambers sealed from the atmosphere, all said chambers having a compressible iiuid therein, said body portion having passages therein each connecting one of said rst mentioned chambers with one of said second mentioned chambers, and a driving member connected centrally with both vsaid last mentioned diaphragms, said connections between said diaphragms and driving member being in alignment with each other, on `opposite sides of said body portion to produce a straight line movement of said driving member.

WILLIAM E. NORVELL. 

